The present invention relates to electroluminescent arrangements, and in particular an electroluminescent arrangement utilizing a light-emitting organic layer system.
Electroluminescent systems are characterized in that light is emitted when an electrical voltage is applied and current is flowing. Systems of this kind have been known for some time under the designation LED (light-emitting diode). Light emission is caused by the fact that positive charge carriers (hereinafter referred to as xe2x80x9cholesxe2x80x9d) and negative charge carriers (electrons) recombine with one another, emitting light. LEDs used in the art generally consist of inorganic semiconductor materials. Also known are electroluminescent systems whose essential constituents consist of organic compounds. LEDs made up of organic compounds have one or more thin layers of organic charge transport compounds. WO 90/13148 describes electroluminescent arrangements in which poly(p-phenylenevinylene) is used. The organic compound performs the function of light emission and electron and hole conduction.
The electroluminescent arrangement according to the present invention has the advantage of making available a new class of compounds for use in electron-conducting layers in LEDs which has not hitherto been used for this purpose. The spectrum of available organic compounds for the production of electroluminescent arrangements is thus considerably expanded. The compounds used according to the present invention, having triazine basic members, are characterized in that they preferentially conduct electrons and block holes. Electroluminescent arrangements with an electron-conducting layer according to the present invention exhibit a considerably higher light intensity than arrangements without said layer.
The present invention concerns, in particular, an electroluminescent arrangement made up of at least two electrodes and a light-emitting layer system comprising at least one electron-conducting layer, the electron-conducting layer containing at least one preferably low-molecular-weight compound having a triazine basic member.
In conjunction with the present invention, a xe2x80x9ctriazine basic memberxe2x80x9d is understood to mean a nitrogen-containing heterocyclic compound of empirical formula C3H3N3 having three nitrogen atoms in a six-membered ring, in particular 1,2,3-triazine, 1,2,4-triazine, and 1,3,5-triazine. The electroluminescent arrangement of the present invention thus comprises at least two electrodes, i.e. an anode and a cathode, and at least one light-emitting layer system having at least one electron-conducting layer, which depending on its nature and composition can also act in light-emitting fashion.
In a particularly preferred embodiment, the compound has a structure of general formula 
in which the organic radicals R1, R2, and R3 are selected from the group of compounds shown below: 
and such that the substituents X, Y, and Z are selected from the group consisting of hydrogen; halogen, oxygen, sulfur atoms; cyanoalkyl, alkyl, alkoxy, arylalkyl, sulfoxyl, sulfonyl, and trifluoromethyl groups; and such that the radical R4 is selected from the group of compounds shown below: 
In addition to the coupling points illustrated, for example 1,4-substitution, all other couplings of R4 are of course also possible and are thus within the scope of the present invention.
In a particularly preferred embodiment, the electroluminescent arrangement of the present invention has multiple layers, in particular an anode applied on a substrate, at least one hole-injecting layer applied on the anode, at least one hole-conducting layer applied on the hole-injecting layer, at least one emitter layer applied on the hole-conducting layer, at least one electron-conducting layer applied on the emitter layer, at least one electron-injecting layer applied on the electron-conducting layer, and a cathode applied on the electron-injecting layer, this substrate/layer system preferably being encapsulated. Of course it is also possible for certain of the aforesaid layers not to be present, but rather for certain, or all, functions, including light emission, to be localized in one layer or a few layers. The electron-conducting layer of the present invention can also perform other functions, for example acting in electroluminescent fashion.
One of the electrodes can be transparent or semi-transparent. A transparent, electrically conductive anode made of a metal oxide, for example indium-tin oxide (ITO), is preferably used.
The cathode is preferably produced from metals such as Mg, Ag, Al, In, etc., which guarantee good electron injection.
For production of the arrangements according to the present invention, the compounds used according to the present invention, which have a triazine basic member, can, for example, be applied by vacuum evaporation onto the electrodes or optionally onto other layers.